[Help!] Battery not Charging Problem

So, the V is currently apart. My attempt to chase the battery not charging problem. I got a pigtail for the alternator flat connector (4-pin, only two middle pins used). Now, before I splice that in, I'd like to see if you guys had any idea what could be causing that problem.

Background. Battery is healthy (12.98V measured just 15 minutes ago) and the engine cranked/fired just fine. All other systems in the car are working properly. The car has stock electronics other than disabled DRL, OnStar and XM radio modules. Driver side engine mount is shot.

The problem started with intermittent "Battery not Charging" message. In the beginning it was rarely displayed so I dismissed it. The frequency and the period increased over time until this past Sunday and the message stayed on solidly (along with the battery light). I thought I might have noticed that when the engine is revved, the message disappeared. I might be wrong on this last point; please take it with a grain of salt for now.

Monday night, I tore into it and took out the alternator. Advance Auto Parts tested it and said it's working just fine. So, the alternator is healthy and is not the culprit.

I moved to the next item. Alternator/battery cables. After disconnecting the one that went to the fuse box under the hood, I measured the resistance between the terminals (alternator terminal and fusebox/battery terminal). Resistance did exist (0.2 ohm). So, it's not the battery or the alternator cables.

The only thing left is the flat-4 connector that plugs into the alternator. What does it do ? If they were to be disconnected or severed, would the DIC think that battery is not being charged ? OR, would the system overcharge the battery ?

This connector has two short wires coming out of a big bundle. Taking the consideration that the engine rocks (likely more than normal due to busted engine mount) when revved, it is possible that the two little wires were pulled to the point that electrical contact was compromised or maybe they were frayed although I could not see anything on the exterior suggesting that they were damaged.

What should I do ? Go ahead and replace the connector with the pigtail (providing more slack too when the engine rocks) ? What if it didn't solve the problem ? What could possibly be the problem if it's not this connector ?

Re: [Help!] Battery not Charging Problem

Originally Posted by darkman

See attached.

I do not have a personal opinion on this, but the scan tool value for the battery is listed at 13.9 volts.

The 12.89V I quoted was measured with the battery disconnected from the car. 13.9V would imply that the alternator was healthy and the engine was running. Before the error message, the alternator was producing north of 14V.

Re: [Help!] Battery not Charging Problem

I had this when the car was under warranty. Dealer eventually fixed it but it turned out to be a wiring harness. I can't remember for the life of me which one it was. It may even have been the PCM wiring. The message is triggered every time voltage slips below 12V when car is running for a period longer than 10 seconds or something similar. Had a tech look it up.

Have you tried disconnecting battery when car is running? This will rule out alternator.

Re: [Help!] Battery not Charging Problem

Originally Posted by ichpen

I had this when the car was under warranty. Dealer eventually fixed it but it turned out to be a wiring harness. I can't remember for the life of me which one it was. It may even have been the PCM wiring. The message is triggered every time voltage slips below 12V when car is running for a period longer than 10 seconds or something similar. Had a tech look it up.

Have you tried disconnecting battery when car is running? This will rule out alternator.

I really hope it's not PCM wiring. I'd just part out this car and chalk it up as a big fail in my life.

If you still have the service receipt, it's probably mentioned there.

No, I have not tried disconnecting the battery when the car is running. However, alternator is already ruled out.

Re: [Help!] Battery not Charging Problem

Because Advance Auto Parts ran the alternator up on the bench, does not mean 'jack'. Because the alternator was not taken apart and an inspection & test of the individual parts ie., stator, rotor, slip rings, rectifier bridge/diodes, brush holder, brush springs & brushes,and the likely culprit the internal 'voltage regulator' was not performed, then, it should NOT be assumed that the alternator is not the problem. I always take the alternator apart and rebuild it, but that's me.
The internal 'voltage regulator' can be an intermittent problem when beginning to fail. The "regulated votage" can be affected by the ambient temperature surrounding it.
So, that's my story ~ speaking from experience.
Hopefully it is not more serious.
good luck.

Re: [Help!] Battery not Charging Problem

Now, if any of those parts you mentioned had failed, wouldn't it have showed up somewhere on that test bench ? They did put a load on the alternator during the test and it passed. The test didn't just spin the alternator and measured the voltage between the terminals.

I can always start throwing parts at the car but it seems unwise. That's why I had the alternator tested. Now, I can bring it to a couple other places and have them test it too.

Another thing is there is actually a thread (showed up on my search) that showed the same symptom(s) and it was not the alternator. ichpen indicated that his problem was due to PCM wiring harness.

Please read my original post again. I indicated that by the time before I removed the alternator, the Battery not Charging message was on solid. No amount of temp difference or whether the engine at low, mid, or high rpm made a difference.

Originally Posted by Stepside

Because Advance Auto Parts ran the alternator up on the bench, does not mean 'jack'. Because the alternator was not taken apart and an inspection & test of the individual parts ie., stator, rotor, slip rings, rectifier bridge/diodes, brush holder, brush springs & brushes,and the likely culprit the internal 'voltage regulator' was not performed, then, it should NOT be assumed that the alternator is not the problem. I always take the alternator apart and rebuild it, but that's me.
The internal 'voltage regulator' can be an intermittent problem when beginning to fail. The "regulated votage" can be affected by the ambient temperature surrounding it.
So, that's my story ~ speaking from experience.
Hopefully it is not more serious.
good luck.

Re: [Help!] Battery not Charging Problem

I re-read your post.
Question: After you had the alternator tested, did you put it back in the car and 'fire it up' to see if it was charging?
It would be easier for you if the internal voltage regulator was 'on the blitz'. When they start to fail, they turn 'on' & 'off' randomly and it can 'drive you up a wall'.
There are two brushes in the alternator that ride on the slip rings of the rotor. If one of them 'hangs up' and then, frees itself, that would cause an intermittent, but I doubt if there is a brush problem.
Hopefully it is not the wiring harness. That sucks, man.Good idea to give a little slack to that connector, cause if it's not connected, it's not charging.
good luck - keep us posted

Re: [Help!] Battery not Charging Problem

The car is still apart and no, I have not tried that. I was/am hesitant to cut off the alternator connector and splice in the new pigtail. That's why I created this thread; hoping that someone may shed a light on it before hacking into anything.

If it was indeed the voltage regulator, I would have thought the voltage would have been outside the limits when tested, no ? Do you know for a fact that if the 4-pin connector (one or both wires) isn't properly connected, the alternator won't charge ?

Maybe this weekend after the race, I'll just suck it up, cut off the connector and splice in the pigtail

Originally Posted by Stepside

I re-read your post.
Question: After you had the alternator tested, did you put it back in the car and 'fire it up' to see if it was charging?
It would be easier for you if the internal voltage regulator was 'on the blitz'. When they start to fail, they turn 'on' & 'off' randomly and it can 'drive you up a wall'.
There are two brushes in the alternator that ride on the slip rings of the rotor. If one of them 'hangs up' and then, frees itself, that would cause an intermittent, but I doubt if there is a brush problem.
Hopefully it is not the wiring harness. That sucks, man.Good idea to give a little slack to that connector, cause if it's not connected, it's not charging.
good luck - keep us posted

Re: [Help!] Battery not Charging Problem

Fact: The two pins being used in the connector is the 'L' & the 'F'.
Voltage is supplied though one of those wires ( L terminal ) to turn on the regulator. That voltage in that wire comes from the PCM. So, the PCM turns on the regulator. The voltage regulator controls current to the rotor by switching 'on' & 'off' at a rate of 400 cycles/second. At low speed, the 'on' time may be 90% and at high speed the 'on' time may only be 10%
. If you turn the ignition switch to 'RUN', there should be current to the 'L' terminal that comes from the PCM.

The 'F' terminal is connected to the voltage regulator and the PCM monitors the 'field' voltage.

I will admit, that I have not had a new (since the '90s) alternator apart, but the technolgy of alternators has been the same since the '60s.

So, if that connector has a poor connection, your alternator will not function properly and your computer will message you.